 var div = new Array()
 div[1] = document.getElementById('theme01');
 div[2] = document.getElementById('theme02');
 div[3] = document.getElementById('theme03');
 div[4] = document.getElementById('theme04');
 div[5] = document.getElementById('theme05');
var a = 1
var b = 0
var c = 0
var scrollFunc = function (e) {  
        e = e || window.event;  
        if (e.wheelDelta || a > 1) {  
        //判断浏览器IE，谷歌滑轮事件 
            if (e.wheelDelta >= 120) { 
            ;//当滑轮向上滚动时 
                b = b + 1;
                if (b % 2 === 0) {  
                  a = a % 6;    
                  c = a - 1;
                  div[c].style.display = 'block';
                  div[a].style.display = 'none';
                  a = a - 1;   
                } 
            }  
            if (e.wheelDelta <= -120) { 
            ;//当滑轮向下滚动时
                b = b + 1;
                if (b % 2 === 0) {
                  a = a + 1;
                  a = a % 6;
                  if (a === 0) {
                    a = a + 1;
                  div[a].style.display = 'block';
                  div[5].style.display = 'none';
                  }
                   else {
                  div[a].style.display = 'block';
                  c = a - 1;
                  div[c].style.display = 'none';
                   }      
                }
            }  
        } else if (e.detail) {  //Firefox滑轮事件  
            if (e.detail> 0) { //当滑轮向上滚动时  
                alert("滑轮向上滚动");  
            }  
            if (e.detail< 0) { //当滑轮向下滚动时  
                alert("滑轮向下滚动");  
            }  
        }  
    } 
    //给页面绑定滑轮滚动事件  
    if (document.addEventListener) {//firefox  
        document.addEventListener('DOMMouseScroll', scrollFunc, false);  
    }  
    //滚动滑轮触发scrollFunc方法  //ie 谷歌  
    window.onmousewheel = document.onmousewheel = scrollFunc; 